Kevin Underhill nails it: "Anyone who does not know their cane conceals a sword or dagger (almost certainly an elderly or disabled person with a second-hand cane) poses no threat, while anyone who does know it will not need, want, or follow this advice."

http://feeds.boingboing.net/~r/boingboing/iBag/~3/YnrmSFhK480/tsa-please-verify-that-your.html